The present invention relates to a flexible tube for an endoscope.
Generally, a flexible tube, which is to be inserted in a human cavity, of an endoscope is provided with an observation window at the tip end portion thereof. Further, in order to identify an orientation of the inserted portion and an inserted depth with respect to an entrance (i.e., a mouth, an anus or the like), indication of a distance from the tip of the insertion portion and the orientation is generally provided. In a conventional flexible tube, as the indication, optically recognizable marks are formed, for example, by printing.
When an optical endoscope is used, when an operator is observing through an eyepiece lens, by simply dropping the eyes a little, the operator can recognize the marks on the insertion portion.
However, when an electronic endoscope, which has spread widely, is used, the observation is usually done through a monitor device such as a CRT monitor, which are usually located at an upper level. Accordingly, when the marks are to be checked, the operator is required to move the sight line by a large amount. Such an action is troublesome. Further, the mark may not be found easily in such a case, and in a worse case, the operator may overlook a diseased portion.